Screaming or howling in Marion County, Oregon

I was a Deputy Sheriff for Marion County from 1970 to 1982. In about 1977, I was dispatched to a reported shooting incident on the Little North Fork Rd., East of Salem and northwest of Gates. The incident involved four young men who were college geology students, camping near the old mining town of Jawbone Flats doing some college work. They were at their camp around 10:00 at night when they heard a howling noise coming from the canyon below their camp site. They later heard the sound of a large animal coming up out of the canyon towards the road near their campsite. They had dogs with them that became scared and hid in the tent. One of the men got a rifle out of the tent and they all went onto the road to try and see what the animal was. When the animal got onto the road, they could not see it clearly as the area was only lit by the light of the moon and the camp fire but they could see the basic outline of the animal. They described it as being huge, maybe eight feet tall and standing on two legs. The animal started coming towards them which, of course, scared them and the young man with the gun fired at it several times. The animal stopped and then crossed the road and continued up the canyon on the other side of the road making a lot of noise as it crashed through the brush. I could not see much during the night so returned the next day to examine the area in day light. I found where the animal had walked up out of the canyon and saw several areas where it had stepped in the unconsolidated rocky hill side of rock and shale and made impressions but none sufficient to identify any characteristic. Several trees of two to three inch diameter were pushed over in the direction the animal travelled, up hill. The distance between the foot steps was at least four feet and that was on a steep uphill walk. I did not find any evidence of the animal being hurt by the gun shots as there was no blood or fur found. I tracked the animal up hill for several hundred yards and then lost the trail in a rocky area. I made a report of this incident and it should be on file. It should be noted that these young men were intelligent college students on a study project and when I interviewed them, were extremely scared by the incident and from my experience, I feel they were telling the truth. There was no other motive I could determine why they would make up this story and then call the police. This incident was never made public.